Ikkitsuukan: Difference between revisions

Ikkitsuukan
Type	Yaku
Kanji	一通 or 一気通貫
English	Straight
Value	2 han; 1 han (open)
Speed	Fast
Difficulty	Easy

VisualWikitext

Revision as of 23:00, 12 June 2024

Ikkitsuukan 「一気通貫」, or ittsuu 「一通」 for short, is a yaku, defined as three distinct tile groups containing 123, 456, 789 of one suit. Collectively, the three groups form a complete single suit straight of 1 through 9. Naturally, in English terms, this hand can also be noted as a "straight", similar to the poker hand of the same name. This hand may be played open or closed. When open, the hand loses value of one han.

Tile diagram

Winning tile: or

Open

Winning tile:

Formation

While the hand shows a complete 1-9 grouping from a particular suit, it is best to view the long cluster as three separate groups of: 123, 456, and 789.

Counter example

Having all the tiles from 1-9 in one suit is not sufficient to compose this yaku - they must form as sequences of 123, 456, 789.

Waiting for: or

In this counter example, the tiles 1-9 for one suit are in the hand, but ittsuu would not be counted. Instead, they are grouped as 123, 567, and 789, with 4-man functioning as the pair.

Discard characteristics

Hands aiming for ittsu often lack a particular suit, as a good number of one suit is collected in the hand.

Compatibility

Main article: Yaku compatibility

^ Ippatsu requires riichi to be of any use.

	RCH	DRI	IPP	SMO	TAN	PFU	IPK	ITT	YAK	SDJ	SDO	TOI	SNA	SNK	CHA	JUN	RPK	SSG	HRO	HON	CHN	CHI	RIN	HAI	HOU	CHK
ITT

Ittsu requires three groups to be sequences, leaving room for only one other tile group. Yaku that require more than one triplet - sanshoku doukou, sanankou, sankantsu, shousangen, toitoi - are thus incompatible. Similarly, sanshoku and ryanpeikou are incompatible because there is no room for their patterns. Chiitoitsu, which does not use mentsu, is likewise incompatible. The 456 sequence invalidates chanta, junchan, and honroutou, while the 123 and 789 sequences invalidate tanyao.

Ittsu can often be combined with honitsu/chinitsu, as the ittsu is already composed of 9 tiles of the same suit. Pinfu also combines well; however, if the ittsu section is not complete, the hand would be subject to to takame and yasume (only one of two waiting tiles would score this yaku).

Vs sanshoku

Main article: Ittsu vs sanshoku

Ittsuu requires three out of the four tile groups to be composed of sequences: 123, 456, and 789. Sanshoku also requires at least three groups of sequences. Sometimes, a hand may be 1-shanten for both yaku because of composition, forcing players to decide one or the other.

External links

一気通貫

Ikkitsuukan in Japanese Wikipedia

@@ Line 39: / Line 39: @@
 {{Yaku compatibility table|ITT}}
-This yaku only leaves room for one tile group of any type, such as a triplet. Therefore, any yaku that requires more than one triplet, including [[sanshoku doukou]], [[toitoi]], [[sanankou]], [[sankantsu]], and [[shousangen]], is deemed incompatible. [[Chiitoitsu]] is likewise incompatible as it does not use [[mentsu]]. [[Tanyao]], [[chanta]], [[junchan]], and [[honroutou]] are incompatible as the 456 group contains no terminals or honours, but the 123 and 789 groups contain terminals. Finally, ittsuu is incompatible with [[sanshoku doujun]] and [[ryanpeikou]] as they each require at least three sequences in a way that are incompatible with the sequences used for ittsuu.
+Ittsu requires three groups to be sequences, leaving room for only one other tile group. Yaku that require more than one triplet - [[sanshoku doukou]], [[sanankou]], [[sankantsu]], [[shousangen]], [[toitoi]] - are thus incompatible. Similarly, [[sanshoku]] and [[ryanpeikou]] are incompatible because there is no room for their patterns. [[Chiitoitsu]], which does not use [[mentsu]], is likewise incompatible. The 456 sequence invalidates [[chanta]], [[junchan]], and [[honroutou]], while the 123 and 789 sequences invalidate [[tanyao]].
-=== With sanshoku ===
+Ittsu can often be combined with [[honitsu]]/[[chinitsu]], as the ittsu is already composed of 9 tiles of the same suit. [[Pinfu]] also combines well; however, if the ittsu section is not complete, the hand would be subject to to [[takame and yasume]] (only one of two waiting tiles would score this yaku).
+=== Vs sanshoku ===
 {{main|Ittsu vs sanshoku}}
-Ittsuu requires three out of the four tile groups to be composed of sequences: 123, 456, and 789.  Sanshoku also requires at least three groups of sequences.  Sometimes, a hand may be 1-shanten from either yaku because of composition.  There comes a point where a player may need to choose one yaku over the other, depending on the circumstances.
+Ittsuu requires three out of the four tile groups to be composed of sequences: 123, 456, and 789.  Sanshoku also requires at least three groups of sequences.  Sometimes, a hand may be 1-shanten for both yaku because of composition, forcing players to decide one or the other.
-=== With pinfu ===
-[[Pinfu]] requires a [[machi|wait pattern]] consisting of [[ryanmen]] (open wait) or a related wait like [[ryanmenten]] (three sided open). If a hand is waiting to complete the 1-9 pattern, a ryanmen wait would be subject to [[takame and yasume]]: only one tile would complete the ittsu.
-However, this problem is completely averted if the hand already contains the full 1-9 pattern, with a wait depending on the extra tile group.
-=== With honitsu and chinitsu ===
-Ittsuu already contains nine tiles (1-9) of a single suit, so [[honitsu]] and [[chinitsu]] naturally combine with ittsuu. To form those yaku, the remaining four tiles (plus one winning tile) have to be composed of the same suit or an honor tile.
-With closed hands, this combination produces some very powerful hands.  With honitsu, the hand produces [[mangan]]; while it is [[baiman]] with chinitsu.
 ==External links==